{"id":"CVE-2026-80976","title":"seg6: reset IP6CB after IPv6 decapsulation","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nseg6: reset IP6CB after IPv6 decapsulation\n\ndecap_and_validate() pulls the outer SRv6 headers and makes the inner\npacket the skb network header. The IPv6 control block …","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-125"],"vendor":"Linux","product":"Linux","affected":["Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < d1f0d353358987ca87f21d8956e2d2854951130d","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < a0e2b0a3718f0cf9fb0ee41710b4a6348a7315c8","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < 9ae92198c24d7dacd4070e2f34f6e1ed3a63061c","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < 96c74420ac92930a7e0f21770818544eee4a93d7","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < 2b154e96fcb3f01fd42765c64e0a56820fbc16eb","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < cfa186a0857a0f831dfca67b16bbc40ecfdf3280","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < c73fb911e02b9a766c950bc9707f3e3a96ffd702","Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < f967455fb2a5a2079b9eb5823e9ccf359174bf9f","Linux 4.14"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:46:00.756Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80976","references":[{"url":"https://git.kernel.org/stable/c/d1f0d353358987ca87f21d8956e2d2854951130d"},{"url":"https://git.kernel.org/stable/c/a0e2b0a3718f0cf9fb0ee41710b4a6348a7315c8"},{"url":"https://git.kernel.org/stable/c/9ae92198c24d7dacd4070e2f34f6e1ed3a63061c"},{"url":"https://git.kernel.org/stable/c/96c74420ac92930a7e0f21770818544eee4a93d7"},{"url":"https://git.kernel.org/stable/c/2b154e96fcb3f01fd42765c64e0a56820fbc16eb"},{"url":"https://git.kernel.org/stable/c/cfa186a0857a0f831dfca67b16bbc40ecfdf3280"},{"url":"https://git.kernel.org/stable/c/c73fb911e02b9a766c950bc9707f3e3a96ffd702"},{"url":"https://git.kernel.org/stable/c/f967455fb2a5a2079b9eb5823e9ccf359174bf9f"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80976.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-80976"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532485"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80976"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80976"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80976.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00714,"epssPercentile":0.53478,"scores":{"cna":9.8,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.455Z","slug":"CVE-2026-80976","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nseg6: reset IP6CB after IPv6 decapsulation\n\ndecap_and_validate() pulls the outer SRv6 headers and makes the inner\npacket the skb network header. The IPv6 control block still contains\nvalues collected while parsing the outer packet, including nhoff and\nextension-header flags.\n\nEnd.DX6 and End.DT6 route the inner IPv6 packet directly to the IPv6\ninput path. An unprivileged user can reach End.DT6 from a user and net\nnamespace by installing a local SID and injecting an outer packet with\nHop-by-Hop and Destination Options headers followed by an SRH and a\nminimal inner IPv6 packet.\n\nThe outer extension headers leave a large nhoff in IP6CB. After\ndecapsulation, ip6_protocol_deliver_rcu() uses that stale offset on the\ninner packet and reads beyond the skb head. KASAN reports:\n\n  BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu\n  ip6_protocol_deliver_rcu+0x1118/0x1450\n  ip6_input_finish+0x11b/0x240\n  seg6_local_input_core+0xed/0x2e0\n  lwtunnel_input+0x1e9/0x4e0\n  ipv6_rthdr_rcv+0x525f/0x6c50\n  ip6_protocol_deliver_rcu+0xcb7/0x1450\n\nBefore clearing IP6CB for an inner IPv6 packet, save its incoming\ninterface index and L3 slave state. Restore both after the clear and set\nnhoff to the inner IPv6 base-header nexthdr field.\n\nUse IP6CB(skb)->iif rather than skb->skb_iif because VRF processing can\nreplace skb_iif with the L3 master while IP6CB keeps the receiving\ninterface. Preserve IP6SKB_L3SLAVE for the same reason.\n\n## Affected\n\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < d1f0d353358987ca87f21d8956e2d2854951130d`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < a0e2b0a3718f0cf9fb0ee41710b4a6348a7315c8`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < 9ae92198c24d7dacd4070e2f34f6e1ed3a63061c`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < 96c74420ac92930a7e0f21770818544eee4a93d7`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < 2b154e96fcb3f01fd42765c64e0a56820fbc16eb`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < cfa186a0857a0f831dfca67b16bbc40ecfdf3280`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < c73fb911e02b9a766c950bc9707f3e3a96ffd702`\n- `Linux >= d7a669dd2f8ba07a17423f4ad586dfc0379882f7 < f967455fb2a5a2079b9eb5823e9ccf359174bf9f`\n- `Linux 4.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80976.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":224795,"id":"CVE-2026-80976","ts":1792401547874,"field":"cvss","old":"7","new":"9.8"},{"seq":224794,"id":"CVE-2026-80976","ts":1792401547874,"field":"severity","old":"high","new":"critical"},{"seq":204185,"id":"CVE-2026-80976","ts":1789490237601,"field":"cvss","old":"9.8","new":"7"},{"seq":204184,"id":"CVE-2026-80976","ts":1789490237601,"field":"severity","old":"critical","new":"high"},{"seq":183813,"id":"CVE-2026-80976","ts":1789356677499,"field":"cvss","old":"9.8","new":"4.7"},{"seq":183812,"id":"CVE-2026-80976","ts":1789356677499,"field":"severity","old":"critical","new":"medium"},{"seq":153156,"id":"CVE-2026-80976","ts":1789285349332,"field":"cvss","old":null,"new":"9.8"},{"seq":153155,"id":"CVE-2026-80976","ts":1789285349332,"field":"severity","old":"none","new":"critical"},{"seq":147171,"id":"CVE-2026-80976","ts":1789270198721,"field":"cvss","old":null,"new":"4.7"},{"seq":147170,"id":"CVE-2026-80976","ts":1789270198721,"field":"severity","old":"none","new":"medium"},{"seq":108920,"id":"CVE-2026-80976","ts":1789183729543,"field":"cvss","old":null,"new":"4.7"},{"seq":108919,"id":"CVE-2026-80976","ts":1789183729543,"field":"severity","old":"none","new":"medium"}]}